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CVE-2021-43799 Detail

Current Description

Zulip is an open-source team collaboration tool. Zulip Server installs RabbitMQ for internal message passing. In versions of Zulip Server prior to 4.9, the initial installation (until first reboot, or restart of RabbitMQ) does not successfully limit the default ports which RabbitMQ opens; this includes port 25672, the RabbitMQ distribution port, which is used as a management port. RabbitMQ's default "cookie" which protects this port is generated using a weak PRNG, which limits the entropy of the password to at most 36 bits; in practicality, the seed for the randomizer is biased, resulting in approximately 20 bits of entropy. If other firewalls (at the OS or network level) do not protect port 25672, a remote attacker can brute-force the 20 bits of entropy in the "cookie" and leverage it for arbitrary execution of code as the rabbitmq user. They can also read all data which is sent through RabbitMQ, which includes all message traffic sent by users. Version 4.9 contains a patch for this vulnerability. As a workaround, ensure that firewalls prevent access to ports 5672 and 25672 from outside the Zulip server.


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score
NIST: NVD
Base Score:  9.8 CRITICAL
Vector:  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Nist CVSS score does not match with CNA score
CNA:  GitHub, Inc.
Base Score:  8.6 HIGH
Vector:  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N


NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: It is possible that the NVD CVSS may not match that of the CNA. The most common reason for this is that publicly available information does not provide sufficient detail or that information simply was not available at the time the CVSS vector string was assigned.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
https://github.com/gteissier/erl-matter Third Party Advisory 
https://github.com/zulip/zulip/commit/a5496f4098e3998c9b84e8dc564aa983d6cdf6e8 Patch  Third Party Advisory 
https://github.com/zulip/zulip/releases/tag/4.9 Release Notes  Third Party Advisory 
https://github.com/zulip/zulip/security/advisories/GHSA-p663-wxvv-2fjp Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) cwe source acceptance level NIST   Contributor acceptance level GitHub, Inc.  

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Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2021-43799
NVD Published Date:
01/25/2022
NVD Last Modified:
02/02/2022
Source:
GitHub, Inc.